Measurement Tools — Underwater Weighing

What It Is

The percent body fat is calculated from equations based on the density of the
body. The density of the body is calculated by an equation that involves
measuring a person suspended on a trapeze in the air and then weighing the
person under water.

Equipment Used

Special weighing scale and submersion pool or tank

How It's Done

The person is seated on a special scale, is submerged in a tank of water,
then exhales as much air as possible.

S/he remains motionless while underwater while the underwater weight is
recorded.

This procedure is repeated two to five times to get a dependable
underwater weight score.

Body density and then percentage of body fat are calculated from the
reading

Pros

It was considered the accepted reference method for many years.

Cons

The equation is based on studies of standard, young Caucasians.
Modifications in the equations may be necessary for other ethnicities.

Some people feel uncomfortable when they must be fully submerged, leading
to incorrect readings.

The procedure requires an experienced operator.

There is always air left in the lungs. It is difficult to accurately
correct for this.

It does not take into account the location of the body fat.

Take Our Survey

We need your help! Periodically we conduct a survey of our visitors and use the results
to help guide our planning process for future programming. We really want to know what
you think, and your answers will help us improve the Shape Up America! organization. Please take
a few minutes to share your questions, thoughts and ideas. Your responses will be kept strictly
confidential.